This invention relates generally to apparatus for growing silicon dendritic web from a melt and, more particularly, to an improved barrier for use in a quartz crucible melt system which enables continuous replacement of the melt.
In the growth of silicon dendritic web in a melt system including an inductively heated susceptor which contains a crucible, melt replenishment has received considerable attention as a means of decreasing costs and improving crystal quality. In such a system, particles or pellets are added at one or both ends of the crucible as the web crystals are grown; however, the heat absorbed in the regions where melting of the replenishment material takes place creates a significant thermal unbalance in the region from which the web is drawn.
The ideal thermal situation would be one that would have a hot region where the pellets are added with the remainder of the crucible being unaffected by additions of material. One approach known to those skilled in the art is the use of one or more barriers within the crucible to localize relatively hot melt replenishment regions from the region from which the dendritic web is drawn. Additionally, various types of thermal modifications have been made by varying the shielding or by moving the induction heating coil; however, these changes tend to provide a linear temperature gradient between the melt region and the growth region which is accompanied by undesirable crystal characteristics. Also, flow of molten silicon from the melt replenishment regions through the barrier disturbs the melt in the growth compartment.